The likely long term damage to your Batfone from a quick dunk in the WC is small. However, it will not work straight away afterwards.
If this happens to you, the first thing to do after removing it from the water is to remove the battery. Not only will it not work, so the battery is not needed, the power might cause extra damage thanks to the shorting out effect of the water.
The important thing is to prevent salt deposits on the printed circuit board so it may need an alcohol paint job. The second thing that happens is that water gets into the keypad bits. These are synthetic rubber with small conductive blobs that short out bits of printed circuit. These have to be dried carefully (please, no hair driers!). Finally, and probably the most stubbortn of all the bits is the part that sends and receives the radio signals. A bit of this is like a tiny box with a lattice holes and tiny flaps. Water here can be most persistent and is probably the bit that takes the longest to dry out.
If the level of urine in the loo was small and therefore the concentration of salts low gentle drying over a few days will be all that is required. If you are a bit of a techie then dismantling the Batfone will speed things up, but please dont poke around inside with screwdrivers and pointy things. Be patient.